Trustcompany, originally known as 41 down, they renamed themselves to trustcompany, I believe due to sum 41 and how similar they sounded so they didn't want to get confused.
I first heard their first song because it was the royal rumble of 2002 theme song, called "falling apart". Ever since then, I've been hooked, but not very many people know about them. They actually went a hiatus between 2005 and 2011 because couple of the members were soon other projects (bands) and it got to be complicated but, they reformed and have had a lot of lineup changes ever since. They haven't released a new album in 4 years, the last one being "dreaming in black and white" back in 2011
Hot Water Music comes to mind-- check out the song Drag My Body. They are a rock band, and they make some great music, and sound great live too.
Animals as Leaders is the most underrated band I can think of. They are instrumental djent, and holy crap, there are pretty much no covers of their stuff on youtube because it is THAT hard to play. Check out "On Impulse" if you are interested.
-Adventures -Animotion -Armoury Show -Blue Zoo -Dr. And The Medics -Five Star -General Public -I-Level -Information Society -It's Immaterial -Kon-Kan -Latin Quarter -Living In A Box -Orange Juice -Red Box -Then Jerico -When In Rome
Tourniquet. Christian thrash metal band, but of course because of the "Christian" label they're not very well known. But I LOVE thrash metal, and they are better than most of the other thrash bands I've heard, even the ones that are much more famous. The skill level of the band members is just fucking miraculous and it sucks that more people can't hear it.